Numerous compounds of the structure of Formula I, especially those in which one of the substituents R.sup.1 to R.sup.5 is an aryloxy group (--OR) adjacent to a ring nitrogen atom, are important herbicides (International Published Patent Application No. WO 94/27974, European Published Patent Application No. 0,053,011, and European Published Patent Application No. 0,447,004).
These known compounds are conventionally synthesized from the corresponding carboxylic acids or carboxylic derivatives (acid chlorides, esters, and nitrites), although these are often difficult to obtain and consequently expensive.